Open Radar

 
Summary:
When transitioning between foreground and background (and vice versa?), if one is using the kAudioUnitSubType_VoiceProcessingIO audio unit, the audio system sometimes breaks down.

A variety of errors are shown; it's unclear exactly how these manifest. With the attached sample app, the following appears in the console when the audio system stops functioning:

ERROR:    [0x16e35f000] >aurioc> 1275: error -308 from GetCurrentFormats

When the VPIO unit is used from The Amazing Audio Engine, the following appears:

18:01:15.867 ERROR:    [0x19e131000] AVAudioSessionUtilities.h:111: GetProperty: AudioSessionGetProperty ('cilt') failed with error: '!siz'
18:01:15.868 ERROR:    [0x19e131000] AVAudioSessionUtilities.h:124: GetProperty_DefaultToZero: AudioSessionGetProperty ('cilt') failed with error: '!siz'
18:01:15.868 ERROR:    [0x19e131000] AVAudioSessionUtilities.h:111: GetProperty: AudioSessionGetProperty ('colt') failed with error: '!siz'
18:01:15.868 ERROR:    [0x19e131000] AVAudioSessionUtilities.h:124: GetProperty_DefaultToZero: AudioSessionGetProperty ('colt') failed with error: '!siz'
18:01:15.868 ERROR:    [0x16e477000] >aurioc> 1275: error -308 from GetCurrentFormats
TAAE: Couldn't activate audio session: Error Domain=NSOSStatusErrorDomain Code=1836282486 "(null)"

TAAE seems to be able to automatically recover from this error by tearing down the audio unit and recreating it.

Steps to Reproduce:
Run the attached sample app.
Repeatedly close and reopen the app (press home button, tap app icon). This needs to be fairly rapid, within about 2 seconds.

Expected Results:
-

Actual Results:
-

Version:
iOS 9.2 beta (13C75)

Notes:


Configuration:
Tested on an iPad Air 2

Attachments:
'AudioTest.zip' was successfully uploaded.